This invention relates to a power generating plant control system for collectively operating and controlling a power generating plant having a plurality of power generating units, and more particularly to a system for controlling in a distributed manner power generating units in a large scale power generating plant by microcomputers provided in every unit.
For example, thermal power generating plants generate steam by means of a boiler by using petroleum, coal or LNG, etc as fuel to introduce this steam into the turbine to rotate the power generator, thus to generate an electric power. Meanwhile, there are instances where such a power generating system is comprised of small scale generating units to use these plural power generating units as a single large scale power generating plant. In order to control the respective generating units in such a power generating plant, it is required to operate or manipulate a large number of equipments in accordance with a complicated procedure. For this reason, ordinarily a large number of plant operators or a large scale automatic system are required such that an operating procedure is stored into the process computer being used.
FIG. 1 is a block diagram showing the entire configuration of a typical power generating plant comprised of a plurality of generating units. In order to operate the power generating unit to generate an electric power output, the following procedure is basically taken.
For the purpose of generating steam, a steam turbine 109 is driven at the number of revolutions of 3000 rpm (or 3600 rpm). Steam thus generated is collected into a condenser 100, at which it is cooled by using sea water. Water cooled at the condenser 100 is delivered from a low-pressure heater 102 to a deaerator 103 by means of a condensate pump 101 through a condensate line 100b. Water subjected to vacuum heat deaeration at the deaerator 103 is delivered to a feed water pump 104 through a feed water line 103a, and is pressurized by the feed water pump 104. Water thus pressurized is delivered from a high-pressure heater 105 to a boiler 106.
In the arrangement of FIG. 1, there is provided a system such that condensed water is returned from the deaerator 103 to the condenser 100 through the line 103b, the internal portion of the boiler 106 and the line 106a, and that feed water is delivered from the exit of the high-pressure heater 105 to the deaerator 103 through the line 105a to the condenser 100 through the internal portion of the boiler 106 and the line 106a. Thus, water can be circulated within the system at the middle stage of starting the unit.
Temperature of water admitted into the boiler 106 is elevated by means of a burner, resulting in high temperature and high pressure steam. The steam from the exit of the boiler 106 goes through a main steam line 106b and is controlled by a steam control valve 107 and a main steam stop valve 108. Thereafter, steam is delivered into the turbine 109. At this time, steam is controlled mainly by the steam control valve 107 so that predetermined rotational frequency is reached.
The rated rotational frequency of the turbine 109 is determined by the frequency of the output of a power generator 110. Namely, the turbine 109 is controlled so that the rated rotational frequency thereof becomes equal to 3000 rpm in the area of the frequency of 50 Hz, and that it becomes equal to 3600 rpm in the area of the frequency of 60 Hz.
The power generator 110 is coupled to the turbine 109 through the central shaft thereof, and the power generator 110 and the turbine 109 rotate at the same number of rotations. Thus, a predetermined generated electric power output is stepped up to the same voltage as the voltage of the power system by a main transformer 112 through a main breaker 111. The voltage thus stepped up is sent to a transmission line 114 of the electric power system through a line breaker 113.
The operation of the power generation unit is basically carried out in accordance with the procedure as stated above. Although not shown in FIG. 1, there are also included a sea water cooling system used for cooling at the condenser 100, a fuel system for carrying out combustion by the burner to heat water at the boiler 106, and an air draft system.
It is to be noted that since a series of procedures for carrying out transformation from water to steam, and transformation from steam to electricity in the entire power generating unit are complex, the configuration corresponding thereto is not included for avoiding such a complexity in FIG. 1.
The power generating unit started and operated in accordance with the above-described procedure is subject to supervisory control by a plurality of operators by using respective dedicated control devices in connection with the control ranges classified as follows.
(i) Control of the condensate system from the condenser 100 to the deaerator 103, and the sea water system used for cooling condensed water.
(ii) Control of the feed water system from the exit side of the deaerator 103 to the high pressure heater 105.
(iii) Control of the system from the feed water at the entrance of the boiler 106 to the steam line 106b on the exit side, the fuel system of the burner for carrying out combustion, and the air draft system.
(iv) Control of the system including the steam control valve 107 for controlling the main steam flow for rotating the turbine 109, the main steam stop valve 108, the turbine 109, and the condenser 100.
(v) Control for exciting the power generator 110 to take out a predetermined electric power to send it to the transmission line 114.
The configuration of a conventional control system including respective dedicated control devices used for operating the above-mentioned power generating unit is shown in FIG. 2.
An operator observes CRT display devices 11, 12 and 13 of an operator console board 1 to give an instruction to a process computer 2 from an operator input device 14 thus to send control signals to respective control devices 6 to 10 of the power generating unit through an input/output processing device 3 of the computer 2.
Further, the operator selects the control or operating switches and push buttons of instruments and/or display devices of the control board 4 while monitoring the state of the power generating unit, thus making it possible to similarly send operation signals for the respective control devices 6 to 10.
In order to start the power generating unit to operate or manipulate it as stated above on the basis of a system instrument or command so that a target load is provided, and to carry out a necessary stop operation depending upon circumstances, a plurality of operators share the manipulation of a large number of operation switches and/or push-buttons by using the control board 4 shown in FIG. 2. Alternatively, an operator gives operation instructions from the operator console board 1 to the process computer 2 while monitoring the plant by means of the CRT display devices provided in the operator console board 1. Thus, control signals are sent to the respective control devices 6 to 10 through the input/output control board 5 or the input/output processing device 3, and inputs for the supervisory control of the plant are taken into the system.
However, with respect to the starting of the power generating unit, there are several kinds of starting patterns in accordance with how many days the power generating unit is stopped. Accordingly, in correspondence with these starting patterns, the power generating unit must be controlled by different operation procedures, respectively.
Furthermore, controls based on various different procedures are conducted in order to optimize the efficiencies of the fuel and the power in correspondence with four kinds of starting modes (very hot, hot, warm and cold) scheduled in advance so as to optimize the starting time.
If an attempt is made to operate the power generating plant by using a conventional control system as stated above, a large scale control system and a plurality of operators for controlling that system are required. As a result, the equipment required therefor and the expense for ensuring the personnel requirement become costly.
In order to operate a plurality of units of the power generating plant by using such a large number of operators and large scale automatic system, a large amount of equipment investment and expenses for educating a large number of operators and maintaining them are required.
It is to be noted that while the invention of the distributed control system is applied to the different type of a power generating plant which is the combined cycle plant being consisted of a gas turbine, a heat recovery boiler and a steam turbine, the technology for collectively operating and controlling relatively small amount of power generated by the combined cycle plant having a plurality of generating units is already disclosed by the inventor of this application which has been issued as U.S. Pat. No. 4,550,379.